Mass Mortality of Invasive Snails: Impact of Nutrient Release on Littoral Water Quality

Liubov Yanygina

doi:10.3390/d13080362

Abstract

Mollusks are the macroinvertebrates most commonly introduced into fresh water. In invaded reservoirs, alien mollusks form a large biomass due to their large size. Climate change, water level regulation, and anthropogenic impacts on the environment lead to the drying up of water bodies and the death of littoral macroinvertebrates. To assess the impact of invasive snail mass mortality on water quality, laboratory experiments on the snail tissue decomposition were performed, the potential release of nutrients into aquatic ecosystems was calculated, and the predicted concentrations of nutrients were verified by field studies. The laboratory experiment showed quick decomposition of the common river snail Viviparus viviparus tissues with release into the environment of ammonium and total phosphorus of 2.72 ± 0.14 mg and 0.10 ± 0.02 mg, respectively, per gram of decomposing tissue. The concentrations of ammonium, nitrates, and total phosphorus at the site of snail death reached 2.70 ± 0.10, 3.13 ± 0.38 and 0.30 ± 0.02 mg/L, respectively. This indicates local contamination of the Novosibirsk reservoir littoral with decomposition products. The aquatic management, water level regulation, and control of undesirable species should take into account the likelihood of water quality decreasing as a result of macroinvertebrate mass mortality.

Highlights

The development of water transport, aquaculture, increased trade in hydrobionts and various human-induced transformations of ecosystems have greatly contributed to the expansion of species beyond their natural habitats
To assess the impact of invasive snail mass mortality on water quality, laboratory experiments on the snail tissue decomposition were performed, the potential release of nutrients into aquatic ecosystems was calculated, and the predicted concentrations of nutrients were verified by field studies
April 2020, mass mortality of V. viviparus was observed in an area of 25,000 m2

Summary

Introduction

The development of water transport, aquaculture, increased trade in hydrobionts and various human-induced transformations of ecosystems have greatly contributed to the expansion of species beyond their natural habitats. Alien species often reach very high abundance in new locations, causing undesirable ecological and economic consequences. A rapid increase in invader abundance followed by its sharp decline occurs in aquatic and terrestrial species as well as in plants and animals [3]. In the case of rapidly changing habitat conditions, the decline in species abundance is accompanied by mass die-offs and the release of decomposition products into aquatic ecosystems. Decomposing tissues release toxicants (e.g., ammonium) into water, causing oppression and even mortality of sensitive species [7]

Methods

Results

Discussion

Conclusion